Mobile communication system, line concentrator, radio base station, mobile station, and communication method

ABSTRACT

A mobile-communications system is disclosed. The system includes a mobile station, a wireless-base station enabled to communicate with the mobile station, and a location-information management apparatus for managing a state of the mobile station in a network layer upper to a link layer for managing wireless-communications resources. The mobile station is provided with wireless-communications means for transmitting and receiving a signal with the wireless-base station in an active state in the link layer for managing the wireless-communications resources, discontinuous-receiving means for discontinuously receiving a control signal from the wireless-base station in the link layer in a state different from the active state, and state-management means for creating a state-transition signal in response to a paging signal included in the control signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a mobile-communicationssystem, and a line concentrator, a wireless-base station, a mobilestation and a communications method for use in the mobile-communicationssystem.

2. Description of the Related Art

In current mobile-communications systems represented by theThird-Generation Mobile-Communications Systems, such method as, forexample, WCDMA (Wideband Code Division Multiple Access) is beingadopted, which method, from a point of view of efficiently usingwireless-communications resources, changes the operational state of amobile station depending on a period in which a packet is neithertransmitted nor received. More specifically, the operational statesconsist of: a first state for using a dedicated channel to communicate(Cell-DCH); a second state such that a dedicated channel cannot be usedbut a common channel can be used (Cell-FACH); a third state fordiscontinuously receiving a control signal from a wireless-base station(Cell-PCH); and a fourth state such that no communications are conductedwith the wireless-base station (Idle). These states are managed in alink layer (L2). In a wireless-access network in which the states of themobile station are managed (UTRAN), which cell the mobile station ineach of the first through third operational states belong to (whichwireless-base station the mobile station is controlled by) is kept trackof. When the cell to which the mobile station belongs changes (when themobile station is handed over), a cell being managed at the UTRAN isalso updated. It is noted that, for the mobile station in the thirdstate, the UTRAN only keeps track of information of the cell lastupdated. Non-Patent Document 1, for example, discloses such amobile-communications system.

On the other hand, in an existing mobile-communications system using anIP-compliant network, the states of the mobile station are managed in anetwork layer or an IP layer (L3) that is upper to the link layer. Thestates consist of a first state enabled to establish a wireless link soas to communicate (Active) and a second state such that the wirelesslink has been released (Dormant). The mobile station in the second statecan receive a first signal (Router Advertisement) for broadcasting suchinformation as which location-registration area is formed by multiplecells and a second signal (Paging Notification) for use in paging amobile station. Configuring such a system makes it possible to alwayskeep track of the location of the mobile station at the system side.

Non-Patent Document 1

Keiji Tachikawa et al., “W-CDMA mobile-communications method”, Maruzen,published Jun. 25, 2001

SUMMARY OF THE INVENTION

It is a general object of the present invention to provide a technologyfor mobile communications that substantially obviates one or moreproblems caused by the limitations and disadvantages of the related art.

It is a more particular object of the present invention to provide amobile communications system, and a line concentrator, a wireless-basestation, a mobile station, and a communications method for use in themobile-communications system that make it possible to suitably deliver apacket signal even when the states of the mobile station that aremanaged in the upper and lower layers do not match.

According to the invention, a mobile-communications system includes amobile station; a wireless-base station enabled to communicate with themobile station; and a location-information management apparatus formanaging the state of the mobile station in a network layer upper to alink layer for managing wireless-communications resources, wherein themobile station is provided with wireless-communications means fortransmitting and receiving a signal with the wireless-base station in anactive state in the link layer for managing the wireless-communicationsresources, discontinuous-receiving means for discontinuously receiving acontrol signal from the wireless-base station in a state different fromthe active state in the link layer, and state-management means forcreating a state-transition signal in response to a paging signalincluded in the control signal,

wherein the location-information management apparatus is provided withstate-management means for managing whether the state of the mobilestation in the network layer is active or idle, and area-managementmeans for managing information regarding a cell to which the mobilestation in the active state belongs and information regarding alocation-registration area to which the mobile station in the idle statebelongs,

wherein a period in which the mobile station in the active state isneither transmitting nor receiving is measured in the link layer and inthe network layer so that the state of the mobile station is changed toa state different from the active state when the period exceeds apredetermined period, wherein a signal destined for a mobile station ina state different from the active state in at least one of the networklayer and the link layer is accumulated in the location-informationmanagement apparatus or said wireless-base station, and the signaldestined for the mobile station is transmitted after the state of saidmobile station is changed to the active state, or discontinuouslytransmitted to the mobile station with the paging signal of the mobilestation created in the wireless-base station, and wherein management ofstate transition of the mobile station in the network layer andmanagement of state transition of the mobile station in the link layerare performed independently.

The mobile-communications system in an embodiment of the invention makesit possible to suitably deliver a packet signal even when the states ofthe mobile station that are managed in the upper and lower layers do notmatch.

Other objects and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a general view of a mobile-communications system in which thepresent invention can be used;

FIG. 2 is a state-transition diagram of a mobile station according tothe present embodiments;

FIG. 3 is a flowchart showing operations in a mobile-communicationssystem according to the present first embodiment;

FIG. 4 is another flowchart showing the operations in themobile-communications system according to the present first embodiment;

FIG. 5 is a flowchart showing operations of a line concentrator in themobile-communications system according to the present first embodiment;

FIG. 6 is a flowchart showing operations of a wireless-base station inthe mobile-communications system according to the present firstembodiment;

FIG. 7 is another flowchart showing the operations of the wireless-basestation in the mobile-communications system according to the presentfirst embodiment;

FIG. 8 is a flowchart showing operations of a mobile station in themobile-communications system according to the present first embodiment;

FIG. 9 is a flowchart illustrating details of a first process performedin a network layer;

FIG. 10 is a flowchart illustrating details of a second processperformed in the network layer;

FIG. 11 is another flowchart showing the operations of the mobilestation in the mobile-communications system according to the presentfirst embodiment;

FIG. 12 is a flowchart illustrating details of a third process performedin the network layer;

FIG. 13 is a flowchart illustrating details of a fourth processperformed in the network layer;

FIG. 14 is a flowchart showing operations of a line concentratoraccording to the present second embodiment;

FIG. 15 is a flowchart showing operations in a mobile-communicationssystem according to the present third embodiment;

FIG. 16 is a flowchart showing operations of a mobile station accordingto the present third embodiment;

FIG. 17 is another flowchart showing the operations of the mobilestation according to the present third embodiment;

FIG. 18 is yet another flowchart showing the operations of the mobilestation according to the present third embodiment;

FIG. 19 is a state-transition diagram of a mobile station according tothe present fourth embodiment;

FIG. 20 is a flowchart showing operations in a mobile-communicationssystem according to the present fourth embodiment;

FIG. 21 is another flowchart showing the operations in themobile-communications system according to the present fourth embodiment;

FIG. 22 is yet another flowchart showing the operations in themobile-communications system according to the present fourth embodiment;

FIG. 23 is a flowchart showing operations of a wireless-base stationaccording to the present fourth embodiment;

FIG. 24 is a flowchart showing operations of a mobile station accordingto the present fourth embodiment;

FIG. 25 is another flowchart showing the operations of the mobilestation according to the present fourth embodiment;

FIG. 26 is a functional block diagram of a mobile station;

FIG. 27 is a functional block diagram of a wireless-base station;

FIG. 28 is a functional block diagram of a concentrator; and

FIG. 29 is a functional block diagram of a location-informationmanagement apparatus.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments of the present invention are describedwith reference to the accompanying drawings.

FIG. 1 is a general view of a mobile-communications system 100 in whichthe present invention can be used. Generally, in the explanations below,an element which appears first in FIG. 1 is given a reference numberwhich starts with “1”, for example. The mobile-communications system 100has an IP network 102 in which communicating is possible with anInternet Protocol (IP)-compliant communications signal (an IP packet).The mobile-communications system 100 has multiple wireless-base stations104, each of which is associated with a cell forming a service area. Thewireless-base station 104 can communicate with a mobile station 106belonging to a cell. A predetermined number of wireless-base stations104 are connected to one line concentrator (hub) 108. The lineconcentrator 108 is connected to the IP network 102. Moreover, themobile-communications system 100 has a location-information managementapparatus 110 connected to the IP network 102 for managing the state, ina network layer (L3), of the mobile station 106. The state of the mobilestation 106 can be managed in the location-information managementapparatus 110 by using a home agent for managing the relationshipbetween a home address and a Care-of-Address of the mobile station 106and a paging agent, etc., for performing paging control of the mobilestation 106.

The mobile station 106 is handed over from one cell to another so as tomake it possible to move within the service area while wirelesslycommunicating. The service area is divided into multiplelocation-registration areas, each of which is formed by a predeterminednumber of cells, and each location-registration area specifies an areafor performing paging of the mobile station 106.

FIG. 26 is a functional block diagram for elements especially related tothe present embodiments out of a variety of functional elements of themobile station 106. The mobile station 106 has a controller 2602, awireless-communications section 2604, a discontinuous receiver 2606, atimer 2608, a packet analyzer 2610, and a state manager 2612. Thecontroller 2602 is for controlling the operations of the variety of thefunctional elements within the mobile station 106. Thewireless-communications section 2604 is a functional section forperforming processes (for example, encoding and decoding, modulating anddemodulating, etc.) for conducting wireless communications between thewireless-base station and the mobile station. The discontinuous receiver2606 is a functional section for receiving, in the below-described idlestate and battery-saving state, a control packet discontinuouslytransmitted from the wireless-base station at timings in line with thetransmission intervals. The timer 2608 is a functional section formeasuring timings for determining whether a transition of theoperational state is required (for example, whether a predeterminedperiod has elapsed). The packet analyzer 2610 is a functional sectionfor determining the contents of a header or a payload of a packetreceived from a wireless-base station. The state manager 2612 is afunctional section for managing what the operational state of the mobilestation is (an active state, an idle state, or a battery-saving state).Information necessary for state management is stored in a storageapparatus 2614.

FIG. 27 is a functional block diagram regarding elements especiallyrelated to the present embodiments out of a variety of functionalelements of a wireless-base station 104. The wireless-base station 104has a controller 2702, a network-communications section 2704, awireless-communications section 2706, an assignment manager 2712, apacket analyzer 2714, and a storage apparatus 2716. The controller 2702is for controlling the operations of a variety of functional elementswithin the wireless-base station 104. The network-communications section2704 is a functional section for performing processes necessary forcommunicating with a network such as the IP network 102 (and with a nodeconnected to the network). The wireless-communications section 2706 is afunctional section for performing processes (for example, encoding anddecoding, modulating and demodulating, etc.) for conducting wirelesscommunications between the wireless-base station and the mobile station.The discontinuous transmitter 2708 is a functional section forperforming processes for discontinuously transmitting a control packetto an idle mobile station not being managed in the assignment manager2712 and a battery-saving mobile station being managed therein. Thetimer 2710 is a functional section for performing timer management inconjunction with the wireless-communications section 2706 and the packetanalyzer 2714 depending on the state of assignment of the mobile stationbeing managed in the assignment manager 2712. The timer managementincludes timing for determining the necessity of transition of theoperational state of the mobile station (for example, timing on whethera certain period has elapsed). The assignment manager 2712 manages theoperational state and the communications state of the mobile stationcontrolled by the wireless-base station. Information necessary for suchmanagement is stored in the storage apparatus 2716. The packet analyzer2714 is a functional section for determining the contents of the headerand the payload of a packet received at the wireless-base station.

FIG. 28 is a functional block diagram of elements especially related tothe present embodiments out of a variety of functional elements of aline concentrator 108. The line concentrator 108 has a controller 2802,a route manager 2804, a network communicator 2806, a packet analyzer2808, and a timer 2810. The controller 2802 is for controlling theoperations of a variety of functional elements within the wireless-basestation 104. The route manager 2804 is a functional section for updating(deleting, changing, adding, etc.) information regarding a route to themobile station (a packet-delivery route). Route information is stored ina storage apparatus 2812. The network manager 2806 is a functionalsection for performing processes necessary for communicating with anetwork such as the IP network 102 (and a node connected to thenetwork). The packet analyzer 2808 is a functional section fordetermining the contents of the header and the payload of a packetreceived via the network. The timer 2810 times and determines whether apredetermined period has elapsed after transferring a packet from theline concentrator to the mobile station. As described below, it ispossible to provide for deleting route information regarding the mobilestation after a predetermined period has elapsed.

It is noted that the line concentrator 108, from a point of view ofspeedily deleting by itself unnecessary route information, is desirablyprovided with the timer 2810. However, the timer 2810 is not mandatoryso that it can be omitted. When omitting, deleting the route informationis performed only with a request from the wireless-base station 106 orthe mobile station 104.

FIG. 29 is a functional block diagram for elements especially related tothe present embodiments out of a variety of functional elements within alocation-information management apparatus. A location-informationmanagement apparatus 110 has a controller 2902, a network-communicationssection 2904, a state manager 2906, an area manager 2908, a packetanalyzer 2910, a paging processor 2912, and a timer 2914. The controller2902 is for controlling the operation of a variety of functionalelements within the location-information management apparatus 110. Thenetwork-communications section 2904 is a functional section forperforming processes for conducting communications with other nodesconnected to a network such as the IP network 102. The state manager2906 is a functional section for managing the states (active, idle) ofthe mobile station in the network layer. Information necessary for thestate management is stored in a storage apparatus for state management2916. The area manager 2908 is a functional section for managing an areafor registering (a location-registration area) when the state beingmanaged in the state manager is the idle state. Information necessaryfor area management is stored in a storage apparatus for area management2918. The packet analyzer 2910 is a functional section for extracting,from a packet received from the network-communications section 2904, andanalyzing the payload. The paging processor 2912 is a functional sectionfor transmitting in conjunction with the area manager 2908 a pagingpacket to all the location-registration areas when a packet destined fora mobile station being managed as idle in the state manager 2906 isreceived by the location-information management apparatus 110. The timer2914 is a functional section for timing a period for which no packettransmissions/receptions are conducted at an active mobile station andfor reporting the fact to the state manager 2906 when the period hasexceeded a predetermined period.

FIG. 2 is a state-transition diagram of a mobile station according tothe present embodiments. The operations of a mobile station are managedusing two states (an active state and an idle state) in both a linklayer (L2) and a network layer (L3). In an active state 202 in the linklayer, the mobile station can communicate via a wireless linkestablished with a wireless-base station. In this case, thewireless-base station keeps track of which mobile station has a wirelesslink established out of the mobile stations controlled by thewireless-base station. In an idle state 204, the wireless link isreleased and the mobile station discontinuously receives a controlsignal transmitted from the wireless-base station. In other words, whilethe mobile station in the active state can transmit/receive a signalwith the wireless-base station, the mobile station in the idle stateonly receives a signal from the wireless-base station.

In an active state 206 in the network layer, the location-informationmanagement apparatus 110 keeps track of which cell the mobile station106 belongs to. In an idle state 208, the location-informationmanagement apparatus 110 keeps track of which location-registration areathe mobile station 106 belongs to. State transitions from the activestates 202, 206 to the idle states 204, 208 can be performed when, forexample, a packet signal is not received in an active state for apredetermined period. The state transition may also be performed using adirect control signal (a trigger) requesting state transition. Moreover,the state transitions from the idle states 204, 208 to the active states202, 206 can be performed for paging a mobile station in order totransfer a packet signal destined for the mobile station and for themobile station to transmit a packet signal.

An important point to note is that, when transitioning between suchstates as described above, whether the state transition in the linklayer is possible is determined by the wireless-base station 104. Forexample, the wireless-base station 104 approves the request from themobile station 106 for establishing a wireless link so that thetransition to the active state 202 is performed. In this case,authorizing, etc., by an upper location-information management apparatus110 is not necessary. Moreover, a further important point to note isthat whether the state transition in the network layer is possible isdetermined by the location-information management apparatus 110. Thus,in the mobile-communications system 100 according to the presentembodiments, the state in the link layer (the lower layer) of the mobilestation 106 is managed by the wireless-base station 104, while the statein the network layer (the upper layer) of the mobile station 106 ismanaged by the location-information management apparatus 110.

A First Embodiment

FIG. 3 is a flowchart showing schematic operations in amobile-communications system 100 according to the present firstembodiment. In the flowchart of FIG. 3, it is assumed that a link layer(a lower layer L2) of a mobile station is managed such that it is in anidle state, while a network layer (an upper layer L3) of the mobilestation is managed such that it is in an active state. It is ideal thatthe states in the link layer and network layer are both idle or bothactive. However, as the states in each of the layers may be managedindependently, a situation in which one of the states is idle and theother active may occur at least temporarily.

In steps 302, 304 it is assumed that a packet signal destined for themobile station 106 arrives at the location-information managementapparatus 110. As the mobile station 106 (or the state in the networklayer of the mobile station 106) is being managed in the active state inthe location-information management apparatus 110, thelocation-information management apparatus 110 tries to transfer thepacket signal to a cell (a wireless-base station) to which the mobilestation 106 belongs.

In step 306 the line concentrator 108 which has received the packetsignal checks whether route information regarding the mobile station 106exists. When a wireless link to the mobile station 106 is established(when it is active in the link layer), meaningful route informationexists. However, in the present case, such route information does notexist as the link layer is idle.

In step 308 when meaningful route-information does not exist, a packetsignal is transmitted by multicast to all wireless base stationsconnected to the line concentrator 108.

In step 310 the wireless-base station 104 which has received a packetsignal checks whether there exists in an assignment table the mobilestation 106 for which the packet signal is destined. The assignmenttable is a list for managing a mobile station which has a wireless linkestablished with a wireless-base station. In the present case, awireless link is not established with the destination mobile station 106so that the destination mobile station 106 discontinuously receives acontrol signal. Therefore, the wireless-base station 104 confirms thatthe destination mobile station 106 is not listed in its own assignmenttable. Then, the packet signal is buffered so as to be held.

In step 312 the wireless-base station 104 creates a paging packet signalfor paging the destination mobile station 106 and includes the pagingpacket signal in a control signal discontinuously transmitted.

In step 314 the destination mobile station 106 that received the pagingpacket signal transmits to the wireless-base station 104 astate-transition report indicating that a wireless link should beestablished so as to transition from the idle state to the active state.The mobile station 104 performs a state transition based on the responsefrom the wireless-base station 104.

In step 316 the wireless-base station 104 that received thestate-transition report establishes a wireless link and updates theassignment table by adding the mobile station 106 to the assignmenttable.

In step 318 the wireless base-station 104 requests the line concentrator108 to add a transfer route of a signal destined for the mobile station106.

In step 320 the line concentrator 104 updates the route information byadding the transfer route in response to the request. The contents ofcommunication of the route information may be, for example, deletingroute information for a certain mobile station, adding route informationfor a newly-connected mobile station, changing route information for acertain mobile station, etc.

In step 322 the line concentrator 108 reports to the wireless-basestation 104 that the transfer route is set up.

In step 328 the mobile station 106 thereafter receives the bufferedpacket signal and communicates with the originator of the signal in theactive operational state in both the upper and lower layers.

In a flowchart shown in FIG. 4, on the other hand, a link layer (a lowerlayer L2) of a mobile station is managed as being active while a networklayer (an upper layer L3) is managed as being idle. In step 402 a packetsignal destined for the mobile station 106 arrives at thelocation-information management apparatus 110. As the destination mobilestation 106 is managed as being idle, the location-informationmanagement apparatus 110 only keeps track of a location-registrationarea of the mobile station 106.

In step 404 the packet signal is buffered and a paging packet signal forpaging the destination mobile station 106 is created. The importantpoint to note is that the paging packet signal in this case is one inthe network layer.

In steps 406 and 408 the paging packet signal is transmitted to all lineconcentrators 108 or wireless-base stations 104 that are included in thelocation-registration area for the mobile station 106. In the presentembodiment, the location-registration area consists of a large number ofcells associated with multiple wireless-base stations connected tomultiple line concentrators.

In step 410 the line concentrator 108 that receives the paging packetsignal checks whether there is a transfer route for the destinationmobile station 106. In the case of the current example, the lower layeris active so that such a transfer route exists.

In step 412, according to the transfer route, the paging packet signalis transferred to the wireless-base station 104.

In step 414, in the wireless-base station 104, an assignment table isinspected. In the case of the current example, a wireless link is set upto the destination mobile station 106.

In step 416 the wireless-base station 104 uses the wireless link totransmit to the mobile station 106 the paging packet signal in thesignal format in the link layer. The mobile station 106 first receivesthe paging packet signal in the signal format in the link layer. Thenthe mobile station 106 extracts the paging packet signal in the networklayer.

In step 420 the mobile station 106 becomes aware that the mobile stationitself is being paged and that the state in the network layer should beactive. Then, the mobile station 106 creates a state-transition reportindicating that such state transition should be performed. Thedestination of the state-transition report is the location-informationmanagement apparatus 110. Such state-transition reporting as describedabove is performed in order to query the location-information managementinformation 110 as to whether it is possible to change the idle state inthe network layer of the mobile station 106 to the active state.

In steps 422 and 424 the state-transition report is transmitted in thesignal format of the link layer to the wireless-base station 104.

In steps 426, 428, and 430 the state-transition report is transmitted tothe line concentrator 108 and is delivered via the IP network 102 to thelocation-information management apparatus 110. In thelocation-information management apparatus 110, the state transition ofthe mobile station is approved, and the state of the mobile station 106in the network layer is changed from the idle state to the active stateand the fact that the state is changed is reported to the mobile station106.

In step 432 the location-information management apparatus 110 transfersto the mobile station 106 the packet signal being buffered so thatsubsequent communications between the mobile station 106 and theoriginator can be performed.

FIG. 5 is a flowchart concerning, out of operations of a lineconcentrator 108, those on transmission of a packet signal that is froma location-information management apparatus 110 to a wireless-basestation 104 controlled by the line concentrator 108. The flow starts atstep 502 and in step 504 the process determines whether the lineconcentrator 108 has received from the location-information managementapparatus 110 a packet signal to be transferred to the wireless-basestation 104 controlled by the line concentrator 108. When the packet isnot received, the flow is immediately terminated.

In step 506, when the packet is received, whether there isroute-information regarding the destination of the packet signal isdetermined.

In step 508, when there is desired route information, the packet signalis transferred to the wireless-base station 104 indicated by the routeinformation.

In step 510, when there is no desired route information, the packetsignal is transmitted by multicast to all wireless-base stations 104connected to the line concentrator 108. Thus, the line concentrator 108transmits the packet signal to the wireless-base station 104 controlledby the line concentrator 108.

Next, a process 512 is performed for deleting unnecessary routeinformation.

In step 514, whether the packet signal is transferred to thewireless-base station is determined.

In step 516, when the packet signal is transferred, the timer isactivated.

In step 518, whether a predetermined period has elapsed is determined.When the predetermined period has elapsed, in step 520, the routeinformation is updated by deleting the route information.

On the other hand, in step 518, when the predetermined period has notelapsed, the process returns to step 514 so that whether the packetsignal has been transferred to the wireless-base station 104 is againdetermined. When the packet signal is newly transferred, the processproceeds to step 516 so that the timer is activated again. When thepacket has not been transferred in step 514, the process proceeds tostep 518 so that whether a predetermined time has elapsed is determined.

Thus, when a packet signal is transferred from the line concentrator 108to the wireless-base station 104, a timer is activated and, when apredetermined period has elapsed without any packet signals being newlytransmitted, the route information for the wireless-base station isdeleted.

FIG. 6 is a flowchart showing, out of operations performed in awireless-base station 104, operations in a case such that a packetsignal is received from the line concentrator 108. This flow starts fromstep 602 so that in step 604 it is determined whether the packet signalis received. When the packet signal is not received, the flow endsimmediately.

In steps 606 and 608, when the packet signal is received, it isdetermined whether the destination mobile station 106 of the packetsignal is included in the assignment table listing all mobile stationswhich have a wireless link established with the wireless-base station104.

In step 610, when the destination mobile station 106 is included, thepacket signal received from the line concentrator 108 is transmitted tothe mobile station 106 via the wireless link set up and proceeds to step618 so that the flow terminates.

In step 612, when it becomes evident that the destination mobile station106 is not included in the assignment table, the packet signal receivedfrom the line concentrator 108 is buffered so as to be held. In thiscase, the destination mobile station 106 is in the idle state ofdiscontinuously receiving a control signal under the control of thewireless-base station 104 or under the control of a differentwireless-base station.

In steps 614 and 615, the wireless-base station 104 creates a pagingpacket signal for paging the destination mobile station 106, andtransmits the paging packet signal to the idle mobile station 106controlled by the wireless-base station 104 using a control signaldiscontinuously transmitted.

FIG. 7 is a flowchart showing, out of operations performed in thewireless-base station 104, those in a case such that a packet signal isreceived from the mobile station 106. This flow starts from step 702 sothat in step 704 whether the packet signal is received from the mobilestation 106 is determined. When the packet is received, the processproceeds to step 706.

In step 706, whether a state-transition report is included in thereceived packet signal is determined. When the report is included, theprocess proceeds to step 708.

In step 708, whether the state-transition report is one requesting astate transition from an idle state to an active state is determined.When the report is one requesting the state transition to the activestate, the process proceeds to step 710.

In step 710, a wireless link is established for the requesting mobilestation 106.

In step 712, the mobile station 106 is added to an assignment table sothat the flow is terminated in step 714.

On the other hand, if the state-transition report as described above isnot requesting the state transition to the active state in step 708, thestate-transition report is one requesting a state transition from theactive state to the idle state.

In step 716, in this case, the mobile station 106 is deleted from theassignment table.

In step 718, a wireless link for the mobile station 106 which is deletedfrom the assignment table is released. It is noted that step 719 is aselective step as described below.

On the other hand, in step 720, when the state-transition report is notreceived in step 706, the packet signal is transferred to thedestination node of the packet signal.

It is noted that the flow is immediately terminated when the packetsignal is not received from the mobile station 106 in step 704.

FIG. 8 shows operations of a mobile station 106 in amobile-communications system 100. The flow starts from step 802. In step804, it is determined whether the mobile station 106 receives a packetsignal from a wireless-base station 104. When it does not receive thepacket signal the flow is immediately terminated, while when it receivesthe packet signal the process proceeds to step 806.

In step 806, a packet signal from the wireless-base station 104 that isreceived in a link layer is inspected so that whether paging in the linklayer is performed is determined. When the paging is not performed, theprocess proceeds to step 810 so that a first process is performed on anIP packet signal extracted from the packet signal inspected in step 806.The IP packet signal has the contents to be processed in the networklayer.

FIG. 9 is a flowchart illustrating details of a first process performedin a network layer (step 810). First, in step 902, the contents of theIP packet signal transmitted from a link layer to the network layer areinspected.

In step 904, whether paging in the network layer is performed on this IPpacket signal is determined. When the paging is not performed, the firstprocess is terminated.

In step 906, when the paging is performed, a packet signal is createdconcerning a state-transition report indicating to thelocation-information management apparatus 110 that the state should bechanged from the idle state to the active state so that the firstprocess is terminated.

In step 818, a further second process in the network layer is performed.

FIG. 10 is a flowchart illustrating details of a second processperformed at the network layer (step 818). In step 1002, the mobilestation 106 inspects a packet signal received from the wireless-basestation 104 and determines whether there is included a response from thelocation-information management apparatus 110 for the state-transitionreport of the network layer.

In step 1004, whether the response exists is determined. When there isno response, a state transition in the network layer is not performed sothat the second process is terminated.

In step 1006, when the response exists, the state in the network layeris changed from the idle state to the active state and the processreturns to step 818 in FIG. 8 so as to proceed to step 820 so that theflow is terminated.

On the other hand, in the link layer, in step 808, when paging isperformed in step 806, a packet signal is created concerning astate-transition report indicating that a state in the link layer shouldbe changed to active.

In step 812, a packet signal is transmitted to the wireless-base station104. In addition to the fact that the packet signal in this caseincludes a state-transition report of the link layer that is destinedfor the wireless-base station 104, when the process of the step 906 isperformed, the packet signal also includes the state-transition reportof the network layer that is destined for the location-informationmanagement apparatus 110.

In step 814, whether there exists a response from the wireless-basestation 104 that is for the state-transition report of the link layer isdetermined. When there is no response, the process returns to step 812.

In step 816, when there is a response from a wireless-base station 104(ACK), the mobile station 106 is added to the assignment table of thewireless-base station 104, a wireless link is established, and the statein the link layer is changed to active.

FIG. 11 illustrates the operations concerning timer processes in thelink layer and the network layer of the mobile station 106 in themobile-communications system 100. This flow starts from a timing asrepresented by a letter (A) between step 804 and step 806 in FIG. 8.First, in step 1102 a timer is activated in the link layer and in step1104 a third process is performed in the network layer.

FIG. 12 is a flowchart illustrating details of a third process performedat the network layer (step 1104). First, in step 1202, a timer in thenetwork layer is activated. In other words, this equates to 2 timersbeing activated in the link and network layers with step 1102 in FIG. 11and with step 1202 in FIG. 12.

In step 1204, whether a predetermined period has elapsed for a timer inthe network layer is determined. When the period has not elapsed, thethird process is terminated.

In step 1206, when the predetermined period has elapsed, a packet signalis created concerning state-transition information indicating that thestate in the network layer should be transitioned to idle. It is notedthat the timer is reset when a further packet signaltransmission/reception is performed before a predetermined period thatis set in advance elapses.

In step 1116, a fourth process (step 1116) is performed in the networklayer.

FIG. 13 is a flowchart illustrating details of a fourth processperformed in the network layer (step 1116). In step 1302, the mobilestation 106 inspects a packet signal received from the wireless-basestation 104 and determines whether a response from thelocation-information management apparatus 110 is included that is forthe state-transition report of the network layer.

In step 1304, whether the response exists is determined. When there isno response, the state transition in the network layer is not performedso that the fourth process is terminated.

In step 1306, when there is such a response, the active state in thenetwork layer is changed to the idle state so that the fourth process isterminated.

When the fourth process of the step 1116 in FIG. 11 is terminated, theprocess proceeds to step 1120 so that the flow is terminated. It isnoted that step 1117 is a selective step that the below-described mobilestation performs.

On the other hand, in the link layer, in step 1106, whether apredetermined period in the link layer has elapsed is determined. Whenthe period has not elapsed, the flow is immediately terminated. Also inthis case, the timer is reset when a transmission or reception of afurther packet signal is performed before a predetermined period set upin advance has elapsed.

In step 1108, when the predetermined period has elapsed, a packet signalis created concerning a state-transition report indicating that thestate in the link layer should be transitioned to idle.

In step 1110, the mobile station 106 transmits a packet signal to thewireless-base station 104. The important points to note are that thispacket signal includes a state-transition report destined for thewireless-base station 104 as well as that, when the process of step 1209in FIG. 12 is performed, the state-transition report destined for thelocation-information apparatus 110 is also included.

In step 1112, whether there exists a response from the state-transitionreport destined for the wireless-base station is determined. When thereis no response, the process returns to step 1110.

In step 1114, when there is such a response, the state of the link layeris changed to idle. In other words, the mobile station 106 is deletedfrom the assignment table in the wireless-base station 104 so as torelease the wireless link for the deleted mobile station 106.

In step 1118, the mobile station 106 performs the process in the idlestate by discontinuously receiving the control signal from thewireless-base station.

A Second Embodiment

FIG. 14 illustrates operations for deleting route information in a lineconcentrator of a mobile-communications system 100 according to thepresent second embodiment. In the first embodiment, a timer is activatedin a line concentrator, and route information is deleted after apredetermined period has elapsed. On the other hand, in the secondembodiment, route information is deleted based on a request from amobile station 106 or a wireless-base station 104. The below-describedflow of FIG. 14 can be executed in lieu of or in addition to the processrepresented by reference number 512 in the flowchart of FIG. 5 of thefirst embodiment.

The flow starts from step 1402 so that in step 1404 the lineconcentrator 108 determines whether a packet signal is received from themobile station 106 or the wireless-base station 104. When the signal isnot received, the flow is immediately terminated.

In step 1406, it is determined whether the packet signal received by theline concentrator 108 is a request to delete the route information.

In step 1408, if deleting the route information is being requested, theroute information for the mobile station 106 indicated in the request isdeleted so that the process proceeds to step 1412 for terminating theflow.

In step 1410, if deleting the route information is not being requested,the packet signal is transferred to the destination of the packet signalreceived by the line concentrator 108 and the flow is terminated.

It is noted that, when the wireless-base station 104 requests to deletethe route information, it is possible to perform the process in aselective step 719 in FIG. 7, for example. Moreover, when the mobilestation 106 requests to delete the route information, it is possible toperform the process in a selective step 1117 in FIG. 11.

As illustrated in the first and second embodiments, informationconcerning a transfer route which is not used for one of transmissionand reception of a packet signal over a certain period can be deletedwith a trigger of a timeout in a line concentrator, a wireless-basestation, or a mobile station.

A Third Embodiment

FIG. 15 illustrates operations in a mobile-communications system 100according to the present third embodiment. As different from the firstand second embodiments, the present embodiment ties a state transitionof one layer to a state transition of the other layer.

In step 1502 and 1506 it is assumed that the location-informationmanagement apparatus 110 sends to an active mobile station 106 a packetsignal via a wireless link managed by the wireless-base station 104.

In steps 1508 and 1510 the mobile station 106 activates a timer in anetwork layer L3 and times a period for which no packet signals aretransmitted/received in response to the fact that a packet signal isreceived from the wireless-base station 104. The timer is reset when afurther packet signal is transmitted or received before a predeterminedperiod set up in advance has elapsed.

In step 1512, when the predetermined period has elapsed in the networklayer, the fact that the period has elapsed is reported to the linklayer. Such reporting is performed using a control signal (a L2 trigger)for communicating between the layers.

In step 1514 the link layer that received the report creates a packetsignal (a state-transition report) indicating that a transition shouldbe made from the active state to the idle state and transmits thecreated packet to the wireless-base station 104.

In step 1516 the wireless-base station 104 updates the assignment tableby deleting the mobile station 106 from the assignment table based onthe state-transition report from the mobile station 106.

In step 1518 a response to the state-transition report (anaffirmative-response signal authorizing a transition to the idle state)is transmitted to the mobile station 106 and a wireless link isreleased.

In step 1520 the mobile station 106 receives the response to thestate-transition report and transfers to idle.

On the other hand, in step 1522 the wireless-base station 104 extractsan IP-packet signal in the network layer from the packet signal in thelink layer and transmits to the location-information managementapparatus 110 via the IP network 102 a packet signal indicating that thestate of the mobile station 106 should be transitioned to idle (astate-transition report).

In step 1524 the location-information management apparatus 110authorizes the contents of the state-transition report and changes thestate of the mobile station 106 from active to idle.

In step 1526 a response signal for the state-transition report arrivesat the wireless-base station 104 that transmitted the state-transitionreport in step 1522. The response signal for the state-transition signalis transmitted to the mobile station 106, the state of the link layer ofwhich mobile station 106 being already idle.

In step 1528 the response signal is transmitted to the mobile station106 using a control signal discontinuously transmitted from thewireless-base station 104.

In steps 1530 and 1532 the mobile station 106 receives the responsesignal for the state-transition report and transitions to the idle statein the network layer.

FIG. 16 shows details of operations of the mobile station 106 in amobile-communications system 100 according to the present thirdembodiment. The flow starting from step 1602 primarily shows operationsin the link layer of the mobile station 106. In step 1604, the mobilestation 106 determines whether a packet signal is received from thewireless-base station 104 and, with respect to this flow, waits untilthe packet signal is received.

In step 1606, when the packet signal is received, the received signal istransferred to the network layer. Then, in step 1608 a first process inthe network layer is performed.

FIG. 17 illustrates details of a first process in the network layer.When a packet signal arrives at the network layer, in step 1702 themobile station 106 activates a timer in the network layer.

In step 1704 it is determined whether a predetermined period haselapsed. When a new signal is transferred from the link layer before thepredetermined period has elapsed, for example, the first process in thenetwork layer is terminated. In this case, a process is performed againstarting from step 1604 in the link layer.

In step 1706, when the predetermined period has elapsed in step 1704, apacket signal is created concerning a state-transition indicating thatthe state in the network layer should be changed to idle.

In step 1708 this packet signal is transferred to the link layer.Moreover, in step 1710 the state-transition in the network layer isreported from the network layer L3 to the link layer L2 using a controlsignal for communicating between the layers (a L2 trigger). Then in step1712 the first process in the network layer is terminated.

Returning to FIG. 16, when the first process in step 1608 is terminated,in step 1610 it is determined whether the L2 trigger is received fromthe network layer. When the L2 trigger is not received, the mobilestation 106 returns to step 1604 so as to wait for a packet signal fromthe wireless-base station 104.

In step 1612, when the L2 trigger is received, a packet signal iscreated concerning a state-transition report indicating that the statein the link layer should be transitioned to idle.

In step 1614 the mobile station 106 transmits to the wireless-basestation 104 a packet signal concerning the state-transition report ofthe link and network layers.

In step 1616 it is determined whether there exists a response from thewireless-base station 104 for the state-transition response of the linklayer. If there is no response, the process returns to step 1614.

In step 1622, when there is a response in step 1616, the statetransition of the link layer is performed so that the link layer becomesidle. In the wireless-base station 104, the mobile station 106 isdeleted from the assignment table and the wireless link is released.

In step 1624 the mobile station 106 performs operations of the idlestate of discontinuously receiving a control signal.

Subsequently, in step 1620 a second process in the network layer isexecuted. In the second process, first a state transition in the networklayer is authorized by the location-information management apparatus 110and whether the response for the state-transition report arrives at themobile station 106 is determined. If the response does not arrive, thesecond process is terminated. If the response arrives, thestate-transition in the network layer is performed so that the statebecomes idle, terminating the second process. Then, the flow isterminated in step 1626.

FIG. 18 shows details of operations of the mobile station 106 in themobile-communications system 100 according to the present thirdembodiment. In the examples illustrated in FIGS. 15 through 17, timermanagement is performed in an upper layer so that a state transition isreported to a lower layer. In a below-described example of FIG. 18, onthe other hand, timer management is performed in a lower layer so that astate transition is reported to an upper layer, thereby maintaining thenature of one state transition being tied to the other state transition.The flow starting from step 1802 primarily shows operations in the linklayer of the mobile station 106. In step 1804, the mobile station 106determines whether a packet signal is received from the wireless-basestation 104 and waits until the packet signal is received with respectto this flow.

In step 1806, when a packet signal is received, the mobile station 106activates a timer in the link layer and measures the time elapsed.

In step 1808 it is determined whether a predetermined period has elapsedso that, when the period has not elapsed, the process returns to step1804.

In step 1810, when the predetermined period has elapsed, the statechange in the link layer is reported to the network layer using the L2trigger.

In step 1812 a predetermined third process is performed in the networklayer that receives such a report. In the third process, a packet signalis created concerning a state-transition report indicating that thestate in the network layer should be changed to idle and the packetsignal is transferred to the link layer.

In step 1814, when the third process is terminated, the mobile station106 transmits to the wireless-base station 104 a packet signalconcerning a state-transition report in the network and link layers.

In step 1816 it is determined whether there exists a response from thewireless-base station 104 for the link-transition report of the linklayer. When there is no response, the process returns to step 1814.

In step 1818, when there is a response, the link layer is caused totransition to the idle state.

In step 1822 the mobile station 106 thereafter performs the process ofthe idle state of discontinuously receiving a control signal.

In step 1820 a fourth process in the network layer is also performed. Inthe fourth process, it is determined whether there exists a response forthe state-transition report of the network layer. When there is noresponse, the fourth process is terminated without performing the statetransition. When there is a response, the state transition in the linklayer is performed so that the state becomes idle, terminating thefourth process and the flow. PS (A Fourth Embodiment

FIG. 19 is a state-transition diagram of a mobile station 106 accordingto the present fourth embodiment. The state of the mobile station 106 inthe present embodiment is managed in two states of an active state andan idle state in a network layer (L3). This point is the same as what isdescribed in FIG. 2. In an active state 1902 in the network layer, thelocation-information management apparatus 110 keeps track of which cellthe mobile station 106 belongs to. In an idle state 1904, thelocation-information management apparatus 110 keeps track of whichlocation-registration area the mobile station 106 belongs to.

The state transition from the active state 1902 to the idle state 1904can be performed when a packet signal is not received over apredetermined period in the active state. It is also possible to performthe state transition by using a direct control signal (a trigger)requesting a state transition. Moreover, a state transition from theidle state 1904 to the active state 1902 can be performed when themobile station 106 is paged in order to transfer a packet signaldestined for the mobile station 106 or in order for the mobile stationto transmit a packet signal, for example.

The state of a mobile station 106 in a link layer (L2) is managed inthree states of active, battery-saving, and idle. This point differsfrom what is described in conjunction with FIG. 2. In an active state1906 in the link layer, the mobile station 106 can communicate through awireless link established with a wireless-base station 104. In thiscase, the wireless-base station 104 keeps track in an assignment tableon which mobile station 106 out of mobile stations controlled by thewireless base-station 104 has a wireless link established. In otherwords, the assignment table includes the fact that the mobile station106 is active and information specifying the wireless link. In abattery-saving state 1910 and an idle state 1908, the wireless link isreleased and the mobile station 106 discontinuously receives a controlsignal transmitted from the wireless-base station 104. While informationconcerning the mobile station 106 in the battery-saving state 1910 ismaintained in the assignment table in the wireless-base station 104,information concerning the mobile station 106 in the idle state 1908 isdeleted from the assignment table. Moreover, as for route informationmanaged in a line concentrator 108, while route information of themobile station 106 in the battery-saving state 1910 is maintained, routeinformation in the idle state 1908 is deleted.

A state transition from the active state 1906 to the battery-savingstate 1910 and a state transition from the battery-saving state 1910 tothe idle state 1908 can be performed when a packet signal is notreceived over a predetermined period or by using a direct control signal(a trigger) requesting a state transition, for example. Moreover, astate transition from the battery-saving state 1910 to the active state1906 and a state transition from the idle state 1908 to thebattery-saving state 1910 can be performed when the mobile station 106is paged in order to transfer a packet signal destined for the mobilestation 106 or in order for the mobile station 106 to transmit a packetsignal, for example. When transitioning between such states as describedabove, the state in a link layer (a lower layer) of the mobile station106 is managed by the wireless-base station 104 while the state in anetwork layer (an upper layer) of the mobile station 106 is managed bythe location-registration management apparatus 110.

FIG. 20 is a flowchart showing operations in a mobile-communicationssystem 100 according to the present fourth embodiment. This flowchart isassociated with operations for the mobile station 106 to transition fromactive to battery-saving. For ease of explanation, it is assumed thatthe upper and lower layers are initially active. In steps 2002, 2004,2006 a packet signal destined for the mobile station 106 is transmittedto the wireless-base station 104 to which the mobile station 106belongs. Then in step 2008 the packet signal is transmitted to themobile station 106 through a wireless link established.

In step 2010, when conducting transmission/reception of a signal withthe wireless-base station 104, the mobile station 106 activates a timer1 in the link layer. Moreover, in steps 2012 and 2014 a timer 2 in thenetwork layer is also activated. In the present embodiment, it isenvisaged that a predetermined period measured by the timer 1 in thelink layer is shorter than a predetermined period measured by the timer2 in the network layer 2.

In step 2016, when a timeout of the timer 1 in the link layer occurs sothat a predetermined period has elapsed, the mobile station 106 createsa packet signal indicating a state-transition report so as to transmitthe created packet signal to the wireless-base station 104. Thestate-transition report indicates that the mobile station 106 shouldtransition from active to battery-saving.

In step 2018 the wireless-base station 104 that received thestate-transition report updates the assignment table by changing thestate of the mobile station 106 being managed in the assignment tablefrom active to battery-saving.

In step 2020 and 2022 the mobile station 106 that receives a response tothe state-transition report releases the wireless link and transitionsto the battery-saving state.

In step 2024 the mobile station 106 that has undergone the statetransition to the battery-saving state activates the timer 2 associatedwith the state-transition to the active state.

In step 2026 the mobile station 106 in this state discontinuouslyreceives a control signal from the wireless-base station 104.

FIG. 21 is a continuation of the flowchart in FIG. 20. In step 2102 themobile station 106 in the battery-saving state discontinuously receivesa control signal.

In step 2104, when the mobile station 106 does not transmit to thewireless-base station 104 a signal over a predetermined period, a packetsignal concerning a state-transition report is created so as to betransmitted to the wireless-base station 104. This state-transitionreport indicates that the mobile station 106 should transition frombattery-saving to idle. As a wireless channel for the mobile station 106to transmit to the wireless-base station 104 the state-transitionreport, a common channel for random access not requiring a dedicatedchannel allocation can be used, for example, but it is not limited tosuch example so that it is possible to use any wireless channel overwhich a state transition can be reported.

In step 2106 the wireless-base station 104 that receives astate-transition report deletes information concerning the mobilestation 106 from the assignment table. Moreover, as illustrated in step2108, a request for deletion of route information concerning the mobilestation 106 is sent to the line concentrator 108.

In step 2110 the line concentrator deletes route information concerningthe mobile station 106 in response to this request.

In step 2112 and 2114 the mobile station 106 that receives a response tothe state-transition report transitions to idle.

In step 2116 the mobile station 106 discontinuously receives a controlsignal from the wireless-base station 104. It is noted that a period ofintermittent reception in the battery-saving state (a period ofdiscontinuous transmission in the wireless-base station) and a period ofintermittent reception in the idle state may be the same, or one may beset longer than the other. For example, a battery-saving mobile stationis likely to revert to active so that, from a point of view of speedilypaging, it is advantageous to set a period of discontinuous transmissionof the battery-saving wireless-base station shorter than a period of theidle one.

The state-transition of step 2114 may be performed after a responsesignal from the wireless-base station 104 is received or immediatelyafter transmitting the state-transition report of step 2104. Moreover,it is also possible that a mobile station 106 that has undergone a statetransition to the battery-saving state and a wireless-base station thathas detected the state transition activate a timer 3 so that after apredetermined period has elapsed, the respective stations individuallyperform a state transition to idle without sending a report on thetransition to idle. In this way, it is advantageous in that both partiesmay perform a state transition without using a common channel as in step2104.

It is noted that when the time measured with the timer 2 of the networklayer that is measured in step 2014 of FIG. 20 exceeds a predeterminedperiod, the procedures (the embodiment 1 through 3) on the statetransitions to idle in the network layer that are described above areexecuted.

FIG. 22 illustrates the operations for paging the mobile station 106 inthe battery-saving state. In steps 2202, 2204 and 2206, when the networklayer is active, a packet signal destined for the mobile station 106 istransmitted to the wireless-base station 104 to which the mobile station106 belongs. Though not illustrated, when the network layer is idle, thepacket signal is transmitted to all wireless-base stations 104 belongingto a location-registration area for the mobile station 106. As describedabove, in the battery-saving state, route information for the mobilestation 106 is maintained in the line concentrator 108 without beingdeleted so that the line concentrator 108 that receives the packetsignal can transfer the packet signal to the wireless-base station 104to which the mobile station 106 belongs.

In step 2208 the wireless-base station 104 inspects the assignment tableso as to determine whether the mobile station 106 is being managed. Inthe battery-saving state, information concerning the mobile station 106is maintained in the assignment table. Then, the wireless-base station104 temporarily buffers the packet signal so as to accumulate thebuffered packet signal. Then the wireless-base station 104 creates apaging packet for paging the mobile station 106 and discontinuouslytransmits the created paging packet.

In step 2210 the mobile station 106 that receives this paging packetcreates a packet signal reporting on a state transition to the idlestate and transmits the created packet signal to the wireless-basestation 104.

In step 2112 the wireless-base station 104 establishes a wireless linkand changes the state of the mobile station 106 in the assignment tableto active.

In step 2214 the wireless-base station 104 uses the established wirelesslink to transmit to the mobile station 106 the accumulated packetsignal.

FIG. 23 is a flowchart showing, out of operations performed in thewireless-base station 104, those when a packet signal is received fromthe mobile station 106. This flow starts from step 2302 so that in step2304 it is determined whether a packet signal is received from themobile station 106. When the packet signal is received, the processproceeds to step 2306.

In step 2306 it is determined whether a state-transition report isincluded in the received packet signal. When the report is included, theprocess proceeds to step 2308.

In step 2308 it is determined whether the state-transition report is onerequesting a state transition to the active state. When the report isone requesting the state transition to the active state, the processproceeds to step 2310.

In step 2310, the state transitions from battery-saving to active. Inthis case, information concerning the mobile station 106 is updated toreflect the active state.

In step 2312 a wireless link is established so that the flow terminatesin step 2314.

On the other hand, when there is no request for the state transition tothe active state in step 2308, in step 2307 it is determined whether thestate-transition report is one requesting a state transition to thebattery-saving state. If the outcome of the determination is negative,the process proceeds to step 2316.

When the process proceeds to step 2316, the state transition to the idlestate is requested. Thus, information concerning the mobile station isdeleted from the assignment table in the wireless-base station 104.

In step 2318 the wireless-base station 104 requests the lineconcentrator 108 to delete route information for the mobile station 106.In the line concentrator 108, the route information is deleted inresponse to this request.

In step 2319 a wireless link is released and the wireless-base station104 discontinuously transmits a control signal to the mobile station 106controlled by the wireless-base station 104.

On the other hand, in step 2320, when the state-transition report is notreceived in step 2306, the packet signal is transferred to thedestination node of the packet signal so that the flow is terminated.

When it is determined in step 2307 that the state-transition report isone requesting a state transition to the battery-saving state, in step2309 the state of the mobile station 106 is changed from active tobattery-saving in the assignment table.

In step 2311 the wireless link is released and the wireless-base station104 discontinuously transmits a control signal to the mobile station 106controlled by the wireless-base station 104 so that the flow isterminated. As described above, the period of the discontinuoustransmission in step 2319 may be the same as or different from what isin step 2311.

FIG. 24 shows operations of a mobile station 106 transitioning to thebattery-saving state. First in step 2402 a timer in the link layer isactivated.

In step 2404, it is determined whether the mobile station 106 hasperformed transmission/reception of a signal with the wireless-basestation 104 so that when the transmission/reception has been performedthe process proceeds to step 2420, immediately terminating the flow.

In step 2406, it is determined whether the timer in the link layer hasexceeded a predetermined period. When it has not exceeded thepredetermined period, the process returns to step 2404.

In step 2408, when the predetermined period has elapsed, a packet signalconcerning a state-transition report is created and is transmitted tothe wireless-base station 104. The state-transition report indicatesthat the state in the link layer should be transitioned from active tobattery-saving.

In step 2412, it is determined whether there exists a response to thestate-transition report destined for the wireless-base station 104. Whenthere is no response, the process returns to step 2408.

In step 2414, when there is a response, the state of the link layer ischanged to the battery-saving state. In other words, while maintainingthe assignment table in the wireless-base station 104 and the routeinformation in the line concentrator 108, the wireless link is released.

As illustrated in step 2418, thereafter the mobile station 106discontinuously receives a control signal from the wireless-base station104.

FIG. 25 shows the operations of the mobile station 106 transitioning tothe idle state. First in step 2502 a timer in the link layer isactivated.

In step 2504, it is determined whether the mobile station 106 hasperformed transmission/reception of a signal with the wireless-basestation 104, and when the transmission/reception has been performed, theprocess proceeds to step 2520 so that the flow is immediatelyterminated.

In step 2506, it is determined whether a timer in the link layer hasexceeded a predetermined period. When it has not, the process returns tostep 2504.

In step 2508, when a predetermined period has elapsed, a packet signalconcerning a state-transition report is created so as to be transmittedto the wireless-base station 104. The state-transition report indicatesthat the state in the link layer should be transitioned from thebattery-saving state to the idle state.

In step 2512, it is determined whether there exists a response to thestate-transition report destined for the wireless-base station 104. Whenthere is no response, the process returns to step 2508.

In step 2514, when there is a response, the state of the link layer ischanged to the battery-saving state. In other words, the wireless linkis released and the assignment table in the wireless-base station 104and the route information in the line concentrator 108 are also deleted.

In step 2518, thereafter the mobile station 106 discontinuously receivesa control signal from the wireless-base station 104.

A Fifth Embodiment

In the mobile-communications system 100 of the first embodiment, thepacket signal destined for the idle mobile station 106 is buffered inthe wireless-base station 104 or location-information managementapparatus 110 so that the packet signal is transmitted aftertransitioning to the active state. In a fifth embodiment, a packetsignal is transmitted without performing such buffering as describedabove. This can be executed as follows, for example. First, it isdetermined whether the mobile station 106 to be the destination of thepacket signal is being managed in the assignment table of thewireless-base station 104. When it is not being managed by the table, apaging packet is created so that the created packet is transmitted tothe mobile station 106 controlled by the wireless-base station with acontrol signal discontinuously transmitted in step 312. In this case,the wireless-base station 104 encapsulates in a packet signal destinedfor the mobile station that is received from the line concentrator 108 apaging signal for the mobile station 106 so that the paging signalencapsulated in the packet signal is discontinuously transmitted.Hereby, it is made possible to transmit, without buffering, a packetsignal to the mobile station 106. Neither buffering nor establishing awireless link is needed so that it is made possible to speedily delivera packet signal.

It is noted that it is possible to perform the same process when thereis also a battery-saving state in the states of the mobile station 106as in the fourth embodiment. In other words, in step 310 an assignmenttable is inspected. When the mobile station 106 is being managed in theassignment table, it is determined whether the state of the mobilestation is active or battery-saving, while when the mobile station 106is not being managed in the assignment table, the mobile station isidle. Thus, the mobile station 106, when not active, can discontinuouslyreceive a packet signal into which is encapsulated a paging signal.

A wireless-base station 104 in the present embodiment performs generallythe same operations as what is illustrated in FIG. 6 so that in step 608the assignment table is inspected. When the mobile station 106 is notbeing managed in the assignment table, the encapsulating as describedabove is performed when creating the paging packet signal in step 614.In other words, an encapsulation is performed on a packet signalreceived from the line concentrator by inserting a paging signal for themobile station 106. Then, in step 616, the wireless-base station 104discontinuously transmits the encapsulated signal.

It is noted that when there may be a battery-saving state, in step 608it is determined whether the mobile station 106 is being managed in theassignment table so that when it is being managed in the table, whetherthe mobile station 106 is active or battery-saving is determined. Whenit is not being managed in the table, the mobile station is idle. Then,the same processes are performed thereafter.

The present application is based on PCT application JP2003/014655, filedNov. 18, 2003, and Japanese Priority Patent Application No. 2002-335720filed Nov. 19, 2002 with the Japanese Patent Office, the entire contentsof which are hereby incorporated by reference.

1. A mobile-communications system, comprising: a mobile station; awireless-base station enabled to communicate with the mobile station;and a location-information management apparatus for managing a state ofthe mobile station in a network layer upper to a link layer for managingwireless-communications resources; wherein said mobile station isprovided with wireless-communications means for transmitting andreceiving a signal with the wireless-base station in an active state inthe link layer for managing the wireless-communications resources,discontinuous-receiving means for discontinuously receiving a controlsignal from said wireless-base station in the link layer in a statedifferent from the active state, and first state-management means forcreating a state-transition signal in response to a paging signalincluded in said control signal, wherein said location-informationmanagement apparatus is provided with second state-management means formanaging whether the state of said mobile station in the network layeris active or idle, and area-management means for managing informationregarding a cell to which the mobile station in the active state belongsand information regarding a location-registration area to which themobile station in the idle state belongs, wherein a period in which themobile station in the active state is neither transmitting nor receivingis measured in the link layer and in the network layer so that the stateof said mobile station is changed to a state different from the activestate when the period exceeds a predetermined period, wherein a signaldestined for the mobile station in the state different from the activestate in at least one of the network layer and the link layer isaccumulated in said location-information management apparatus or saidwireless-base station, and the signal destined for said mobile stationis transmitted after the state of said mobile station is changed to theactive state, or discontinuously transmitted to said mobile station withthe paging signal of said mobile station created in said wireless-basestation, and wherein management of state transition of the mobilestation in the network layer and management of state transition of themobile station in the link layer are performed independently.
 2. A lineconcentrator connected to a plurality of the wireless-base stationswhich line concentrator is for use in the mobile-communications systemas claimed in claim 1, comprising: communications means for relaying thesignal between said location-information management apparatus and thewireless-base station; and route-management means for managing routeinformation indicating a transfer route of the signal to said mobilestation.
 3. The line concentrator as claimed in claim 2, furthercomprising: timer means for timing a period for which a signaltransmission associated with the mobile station is not being performed;and route-management means for deleting the route information for saidmobile station from storage means when the timed period exceeds apredetermined period.
 4. The line concentrator as claimed in claim 2,further comprising: route-management means for updating the routeinformation for said mobile station based on a request from said mobilestation or said wireless-base station.
 5. The line concentrator asclaimed in claim 2 that is further connected to a plurality of thewireless-base stations, wherein, when the signal destined for the mobilestation is received and when the route information regarding said mobilestation is not stored in storage means, said signal destined for themobile station is transmitted to said wireless-base stations.
 6. Theline concentrator as claimed in claim 2, wherein said route-managementmeans maintains the route information of said mobile station operatingin a battery-saving state in the link layer that is different from theactive state, while the route information of said mobile stationoperating in an idle state different from said active state is deleted.7. A location-information management apparatus for use in amobile-communications system having a mobile station for conductingwireless communications in an active state in a link layer and fordiscontinuously receiving a control signal in a state different fromsaid active state, and a wireless-base station for communicating withthe mobile station, comprising: state-management means for managingwhether the state of the mobile station in a network layer upper to thelink layer for managing wireless-communications resources is active oridle; area-management means for managing information regarding a cell towhich the mobile station in said active state belongs and informationregarding a location-registration area to which said mobile station insaid idle state belongs; and timer means for timing a period in which asignal transmission associated with the mobile station is not beingperformed; wherein the state of said mobile station in the network layeris changed to a state different from the active state when the periodexceeds a predetermined period, and wherein, when a signal destined forthe mobile station in the idle state in the network layer isaccumulated, a paging signal for paging said mobile station istransmitted to a plurality of the wireless-base stations, astate-transition signal created by said mobile station in response tosaid paging signal is received, and the signal accumulated that isdestined for said mobile station is transmitted in response to astate-transition report indicating that the mobile station undergoes astate transition.
 8. A wireless-base station for use in amobile-communications system having a location-information managementapparatus for managing a state of a mobile station in a network layerupper to a link layer, comprising: communications means for wirelesslycommunicating with the mobile station in an active state in the linklayer for managing wireless-communications resources;discontinuous-transmitting means for discontinuously transmittingcontrol information to the mobile station in a state different from saidactive state; management means for managing information pertaining tothe mobile station wirelessly communicating; and timer means for timinga period in which the mobile station in the active state neithertransmits nor receives; wherein, in the location-information managementapparatus, whether the state of said mobile station in said networklayer is active or idle is managed, and information regarding a cell towhich the mobile station in said active state belongs and informationregarding a location-registration area to which the mobile station insaid idle state belongs are managed, wherein the state of said mobilestation is changed to a state different from the active state when theperiod timed with said timer means exceeds a predetermined period, andwherein, when a signal destined for the mobile station in a statedifferent from the active state is received in the link layer, astate-transition signal created by said mobile station in response to apaging signal for paging said mobile station is received, and inresponse to the state-transition signal indicating that a statetransition should be performed, the signal accumulated that is destinedfor said mobile station is transmitted, or the paging signal and thesignal destined for said mobile station are discontinuously transmitted.9. The wireless-base station as claimed in claim 8, wherein saidmanagement means deletes information pertaining to the mobile stationtransitioned to the idle state in said link layer that is different fromthe active state from an assignment table for managing a mobile stationwhich establishes a wireless link so as to communicate.
 10. A mobilestation enabled to communicate with a wireless-base station, comprising:wireless-communications means for transmitting and receiving a signalwith the wireless-base station in an active state in a link layer formanaging wireless-communications resources; discontinuous-receivingmeans for discontinuously receiving a control signal from saidwireless-base station in a state different from said active state;state-management means for creating a state-transition signal inresponse to a paging signal included in said control signal; and timermeans for timing a period in which neither transmission nor receptiontakes place in said active state; wherein whether a state of said mobilestation in a network layer upper to the link layer is active or idle ismanaged by a location-information management apparatus, and in thelocation-information management apparatus, information pertaining to acell to which said mobile station in said active state belongs andinformation pertaining to a location-registration area to which saidmobile station in said idle state belongs are managed, wherein the stateof said mobile station transitions to a state different from the activestate when the period timed with said timer means exceeds apredetermined period, and wherein, when in a state different from theactive state in at least one of said network layer and said link layer,after said state-transition signal is transmitted, the signalaccumulated in said location-information management apparatus or saidwireless-base station is received, or the paging signal and a signaldestined for the mobile station itself are discontinuously received fromsaid wireless-base station.
 11. The mobile station as claimed in claim10 that is further adopted to change, in response to changing the statein one of said link layer and said network layer, the state of the otherof said link layer and said network layer.
 12. A communications methodfor use in a mobile-communications system consisting of a mobilestation, a wireless-base station enabled to communicate with said mobilestation, and a location-information management apparatus for managing astate of the mobile station in a network layer upper to a link layer formanaging wireless-communications resources, comprising the steps of: themobile station, in an active mode in said link layer for managing thewireless-communications resources, receiving a signal from thewireless-base station; timing, in the link layer and in the networklayer, a period in which said mobile station neither transmits norreceives after receiving said signal; transmitting to said wireless-basestation, when the period timed in the link layer has exceeded apredetermined period, a state-transition signal indicating that a statein the link layer of said mobile station should transition to a statedifferent from the active state; transmitting to saidlocation-information management apparatus, when the period timed in thenetwork layer has exceeded a predetermined period, a state-transitionsignal indicating that the state in the network layer of said mobilestation should transition to an idle state; and said mobile stationdiscontinuously receiving a control signal from said wireless-basestation in the link layer in a state different from the active state.